Eccentric Casing System

Your Professional ODEX Eccentric Casing System Manufacturer

An ODEX (Overburden Drilling with Eccentric) system is a casing advancement method designed for drilling through unstable overburden formations where hole collapse is a constant risk. As a leading manufacturer in China, MSD (Zhuzhou Jingde Machinery Co., Ltd.) has spent over two decades perfecting ODEX system design and production. Our expertise ensures every ODEX system we produce delivers reliable hole stabilization and exceptional field performance, whether for water well, foundation, or anchor drilling applications.

What Is an ODEX Eccentric Casing System?

An ODEX (Overburden Drilling with Eccentric) system is a casing advancement method designed for drilling through unstable overburden formations where hole collapse is a constant risk. The system allows simultaneous drilling and casing installation—the eccentric reamer expands during forward rotation to drill a hole larger than the casing OD, while the casing follows directly behind, preventing collapse. When target depth is reached, reverse rotation retracts the reamer, allowing the drilling tools to be retrieved while leaving the casing in place.

MSD ODEX System Components

A complete MSD ODEX system consists of six integrated components that work together as a unified drilling solution. The casing tube uses steel pipes with threaded or welded connections (left-hand thread) that remain in the hole to stabilize the borehole wall. Drill pipes connect the rig to the hammer, transmitting rotation, thrust, and compressed air with thread options including API REG, IF, and NC. A centralizer keeps the drill string centered within the casing. The impactor (DTH hammer) provides percussive energy to drive the pilot bit and eccentric reamer with API REG thread connection. The casing shoe (tube boot) attaches to the bottom of the casing string with threaded or welded connection options. Finally, eccentric drilling tools form the core component, including the pilot bit, eccentric reamer, and locking system that expands eccentrically during drilling then retracts for tool retrieval.

How ODEX Works: Operating Sequence

Step 1 - Drilling: During forward (right-hand) rotation, the eccentric wheel turns outward, expanding the reamer to cut a hole larger than the casing diameter. The casing advances simultaneously behind the expanding bit.

Step 2 - Retraction: At target depth, carefully reverse rotation. The eccentric mechanism retracts the reamer back within the casing diameter.

Step 3 - Casing Installation: The casing remains in the hole for permanent installation or grouting. The retracted drilling tools are pulled up through the casing.

Step 4 - Continued Drilling: Once through the overburden, continue drilling into stable bedrock with conventional DTH tools.

MSD ODEX Design Advantages

Reinforced Locking Mechanism: The most catastrophic ODEX failure is losing the bit in the hole when locking pins shear off. MSD has redesigned the pilot bit and eccentric reamer engagement structure with locking pins forged from ultra-high-toughness alloy steel. This delivers 20%+ higher shear resistance than standard designs, dramatically reducing the risk of underground bit loss.

Improved Eccentric Wheel Durability: MSD has modified the eccentric wheel structure to increase wear resistance on the back side of the reamer, extending service life in abrasive formations.

Easy Retrieval Design: The threaded end of the eccentric drill bit features a deformation yielding zone that facilitates disassembly even after extended drilling campaigns in difficult conditions.

System Integration: MSD provides complete casing advancement solutions—ODEX tools, drill pipes, hammers, and centralizers are all engineered to work together seamlessly, ensuring maximum reliability and drilling efficiency.

ODEX Application Scope

Water Well Drilling: ODEX is the primary tool for water well drilling in unstable formations. It enables simultaneous drilling and wall protection, significantly shortening the time to penetrate overburden layers and reach the aquifer.

Foundation Support: In geological conditions with mud, sand, and clay, ODEX is the fastest and most economical drilling system when steel pipe is needed to protect the borehole wall permanently or temporarily.

Anchor Drilling: When slope stabilization or rock anchoring is required, ODEX effectively meets the requirements of anchoring engineering projects.

Applicable Formations: Loose surface materials including soil, clay, weathered rock, sand, gravel, and small-grained pebble layers. Effective for casing depths within 30-50 meters in standard conditions.

When ODEX Reaches Its Limits — And When to Switch to Symmetrix

MSD believes in honest technical guidance. ODEX is not suitable for every situation. You must switch to a Symmetrix concentric system when massive boulders are present—the eccentric reamer is single-sided and cannot handle direct impact with large boulders, and the unbalanced force can shear off the reamer or locking pins. When overburden exceeds 50 meters, the slight spiral deviation inherent in eccentric drilling accumulates over depth, creating friction that can prevent casing advancement beyond 40-50 meters. For large diameters exceeding 273mm, centrifugal force and vibration from eccentric rotation become severe, potentially damaging the hammer and rotary head. And when strict hole straightness is required for precision foundation piling requiring strict verticality, concentric drilling is mandatory.

MSD ODEX Product Range

Small Diameter (ODEX85-98): Casing OD 108-127mm, for DHD3.5 hammers. Ideal for small water wells and light anchor drilling. Popular for drilling depths 20-30 meters.

Medium Diameter (ODEX115-165): Casing OD 145-194mm, for DHD340/350/360, QL40/50/60, SD4/5/6 hammers. This is MSD's most popular range for water well and foundation applications. Proven for drilling depths 30-50 meters through diverse unstable formations.

Large Diameter (ODEX190-280): Casing OD 219-325mm, for DHD360/380, QL60/80, SD6/8/10 hammers. Heavy-duty applications approaching ODEX system limits. Suitable for complex overburden conditions and specialized anchor projects.

Proven Field Performance

MSD ODEX systems are deployed globally by 500+ drilling contractors, with proven reliability in demanding water well, foundation, and anchor drilling applications.

South Africa Water Well Project: MSD ODEX 114 system (with 4.5" casing) was deployed in a drought-region water well program drilling through 40 meters of unstable overburden—alternating loose sand, clay, and collapsible fractured gravel—before reaching solid bedrock. Result: 100% hole completion rate across 36 consecutive water wells. Zero hole collapses, zero lost bits in hole. Client feedback confirmed drilling speed matching tier-1 European brands while reducing total tooling consumption cost by 35%.

Why Drilling Contractors Trust MSD ODEX Systems

ODEX delivers 80% of Symmetrix capability at 60% of the cost. For standard overburden drilling in water well, foundation, and anchor applications, MSD ODEX systems provide the reliability contractors need at a total cost of ownership 30-50% lower than European brands. Trusted by 500+ drilling contractors in 40+ countries, MSD delivers OEM-grade quality at China factory pricing. Our manufacturing base in Zhuzhou—China's tungsten carbide capital—provides direct access to premium materials and ensures high stock availability on popular sizes for fast global delivery.

Why Partner with MSD?

Beyond manufacturing, we provide complete casing drilling solutions. Our engineers analyze your project's overburden geology and drilling depth to recommend the ideal ODEX system size, hammer type, and drill pipe configuration. We help you determine when ODEX is appropriate and when to transition to Symmetrix concentric casing for specific geological conditions. By optimizing the entire drilling system, we help you achieve maximum drilling speed, minimize tool loss risk, and reduce total cost per hole. With massive inventory across all ODEX sizes and agile production capability, we ensure your project stays on schedule. Trust MSD for reliable ODEX systems and expert technical support that drive your drilling profitability.

Technical content reviewed by MSD Engineering Team. | About MSD: Zhuzhou Jingde Machinery Co., Ltd. — 23+ years of rock drilling tools manufacturing expertise | ISO 9001 Certified | Serving 500+ contractors in 40+ countries